I've never received such bad customer service

My Fibre contract was signed for cancellation on the 31 Dec 2018. Vodacom Billed me for Jan, Feb and March 2019. I phoned every month, complained and asked for someone to call me back to tell me why Vodacom keep billing me. I got no response. The person on the other side keep telling me they will send Dominique an email and ask him to phone me back or to resolve the matter. I keep calling every month Vodacom owes me more than R2000. No one calls me back and the credit still doesn't show on my account. My account with Vodacom is about R8000 every month I'm going to cancel all my contracts as soon as the period expires.